Hybrid vehicles are characterized by the combination of an internal combustion engine and an electric motor as motive agents. Usually two types are differentiated, namely, parallel hybrid vehicles and series hybrid vehicles. In the case of series hybrid vehicles, the electric motor and internal combustion engine are permanently linked, whereas in the case of parallel hybrid vehicles, the two drive units may be selected concurrently, as well as each on its own for the drive unit. Moreover, it is conventional to use the electric motor for starting the internal combustion engine in order, among other things, to realize a start-stop function, as well.
German Published Patent Application No. 103 02 860 describes a method and a device for determining a strategy for the operation of a battery, including at least one measuring device, at least one evaluation device as well as a control device; voltage and current as well as at least one further state variable of the battery being measurable by the measuring device; based on the at least one further measured state variable as well as on fixed quantities of the battery and/or quantities derived therefrom, the evaluation device being able to generate a dynamic operating window that defines an operating range of the battery within which the battery can be operated without exceeding or dropping below critical values of state variables of the battery; an instantaneous operating point of the battery being determinable based on the measured voltage and the measured current of the battery; with the aid of the dynamic operating window, at least one limit value of at least one state variable of the battery being determinable as a function of the operating point of the battery within the operating window; and the transmitted limit value being able to be included in the control process of the units operated in connection with the battery. Preferably, at least the temperature is measurable by the measuring device as a further state variable of the battery.
German Published Patent Application No. 102 94 242 describes a drive unit for a vehicle that uses a generator motor, which is activated by an electric current supplied from am accumulator, in order to power a vehicle, and which assists a motive internal combustion engine in a vehicle; including a temperature detector that detects a temperature of the accumulator; a current-value detector which detects the current value input into the accumulator and output from it; a computing device which calculates a permissible current value that may be input into the accumulator and output from it, on the basis of a difference between a temperature of the accumulator and a predetermined upper limit temperature, when the temperature of the accumulator exceeds a threshold temperature; a current-value determining device which determines whether the current value which is input into the accumulator and output from it exceeds the permissible current value; and a command-value corrector which reduces a torque command value of the generator motor when the current-value determining device determines that the current value which is input into the accumulator and output from it exceeds the permissible current value.